linux-stable.git/drivers/base/property.c, branch linux-5.6.y

device property: Add a function to obtain a node's prefix

2019-10-11T09:26:55+00:00

The prefix is used for printing purpose before a node, and it also works
as a separator between two nodes.

Signed-off-by: Sakari Ailus 
Acked-by: Rob Herring  (for OF)
Reviewed-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

device property: Add fwnode_get_name for returning the name of a node

2019-10-11T09:26:55+00:00

The fwnode framework did not have means to obtain the name of a node. Add
that now, in form of the fwnode_get_name() function and a corresponding
get_name fwnode op. OF and ACPI support is included.

Signed-off-by: Sakari Ailus 
Acked-by: Rob Herring  (for OF)
Reviewed-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

device property: Add functions for accessing node's parents

2019-10-11T09:26:55+00:00

Add two convenience functions for accessing node's parents:

fwnode_count_parents() returns the number of parent nodes a given node
has. fwnode_get_nth_parent() returns node's parent at a given distance
from the node itself.

Signed-off-by: Sakari Ailus 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

device property: Move fwnode_get_parent() up

2019-10-11T09:26:55+00:00

Move fwnode_get_parent() above fwnode_get_next_parent(), making the order
the same as in the header file.

Signed-off-by: Sakari Ailus 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

device property: Introduce fwnode_find_reference()

2019-06-03T08:55:38+00:00

In most cases the references that the drivers look for don't
have any arguments. This introduces a wrapper function for
fwnode_property_get_reference_args() that looks for
references by using only the name and index.

Signed-off-by: Heikki Krogerus 
Tested-by: Hans de Goede 
Signed-off-by: Rafael J. Wysocki

device property: Add fwnode_graph_get_endpoint_by_id()

2019-04-18T14:44:05+00:00

fwnode_graph_get_endpoint_by_id() is intended for obtaining local
endpoints by a given local port.

fwnode_graph_get_endpoint_by_id() is slightly different from its OF
counterpart, of_graph_get_endpoint_by_regs(): instead of using -1 as
a value to indicate that a port or an endpoint number does not matter,
it uses flags to look for equal or greater endpoint. The port number
is always fixed. It also returns only remote endpoints that belong
to an available device, a behaviour that can be turned off with a flag.

Signed-off-by: Sakari Ailus 
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki

device property: fix fwnode_graph_get_next_endpoint() documentation

2018-12-18T22:39:45+00:00

Sync documentation with code.

Fixes: 07bb80d40b0e (device property: Add support for remote endpoints)
Signed-off-by: Marco Felsch 
Acked-by: Sakari Ailus 
Signed-off-by: Rafael J. Wysocki

device property: Remove struct property_set

2018-11-26T17:19:11+00:00

Replacing struct property_set with the software nodes that
were just introduced.

The API and functionality for adding properties to devices
remains the same, however, the goal is to convert the
drivers to use the API for software nodes when the device
has no real firmware node, and use the old API only when
"extra" build-in properties are needed.

Signed-off-by: Heikki Krogerus 
Acked-by: Linus Walleij 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

device property: Move device_add_properties() to swnode.c

2018-11-26T17:19:11+00:00

Concentrating struct property_entry processing to
drivers/base/swnode.c

Signed-off-by: Heikki Krogerus 
Acked-by: Linus Walleij 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

device property: Get rid of union aliasing

2018-05-17T10:47:21+00:00

Commit 318a19718261 (device property: refactor built-in properties
support) went way too far and brought a union aliasing. Partially
revert it here to get rid of union aliasing.

Note, all Apple properties are considered as u8 arrays. To get a value
of any of them the caller must use device_property_read_u8_array().

What's union aliasing?
~~~~~~~~~~~~~~~~~~~~~~

The C99 standard in section 6.2.5 paragraph 20 defines union type as
"an overlapping nonempty set of member objects". It also states in
section 6.7.2.1 paragraph 14 that "the value of at most one of the
members can be stored in a union object at any time'.

Union aliasing is a type punning mechanism using union members to store
as one type and read back as another.

Why it's not good?
~~~~~~~~~~~~~~~~~~

Section 6.2.6.1 paragraph 6 says that a union object may not be a trap
representation, although its member objects may be.

Meanwhile annex J.1 says that "the value of a union member other than
the last one stored into" is unspecified [removed in C11].

In TC3, a footnote is added which specifies that accessing a member of a
union other than the last one stored causes "the object representation"
to be re-interpreted in the new type and specifically refers to this as
"type punning". This conflicts to some degree with Annex J.1.

While it's working in Linux with GCC, the use of union members to do
type punning is not clear area in the C standard and might lead to
unspecified behaviour.

More information is available in this [1] blog post.

[1]: https://davmac.wordpress.com/2010/02/26/c99-revisited/

Signed-off-by: Andy Shevchenko 
Acked-by: Ard Biesheuvel 
Reviewed-by: Mika Westerberg 
Signed-off-by: Rafael J. Wysocki